Need a little help

[COLEBABIE]

Needing a little help, have a steer looking at using melatonin in for a bit of  a calming effect and hair coat . Can you guys tell me how much to use, how often and what mg? I bought 3 mg. I had a vet tell us once to use abt 20 tabs but i forget how often and what mg it was. Any help would be great.